The phosphohydroxylysine phospholyase, a pyridoxal phosphate enzyme which has been purified from rat liver, will be investigated in cooperation with Dr. E.E. Snell at the University of California. Attempts will be made to purify the enzyme to homogeneity such that the mechanism, subunit structure and control can be investigated. Lower forms will be studied to determine how general the phosphorylation pathway is used for degrading hydroxylysine. Efforts will be continued with human tissues to determine the importance of the enzymes which function in the rat in hydroxylysine degradation. If the methods can be refined and perfected sufficiently it is hoped that persons working with hydroxylysinemia can be invited to submit needle biopsy samples of liver for examination.